1. Field
The present invention relates to a radio communication apparatus executing radio communications accompanying authentication procedure of, for example, Bluetooth®, etc.
2. Description of the Related Art
In Bluetooth Core Specification version 2.1+EDR, a new connection authentication procedure called Secure Simple Pairing (hereinafter abbreviated as SSP) is defined. The SSP has two objects. One of the objects is to improve usability by simplifying the authentication procedure. The other object is to improve security by introducing a public key encryption system and reinforcing resistance to passive eavesdropping and man-in-the-middle or active eavesdropping.
Next, a procedure for authentication between Device A and Device B will be explained. A shape of Device A enables the device to display numbers and to input numbers and Yes/No. Device B has any shape (the authentication processing is classified according to the shape of Device B).
The conventional authentication procedure (Bluetooth Core Specification version 2.0+EDR) has urged a user to input, for example, a common decimal four-digit PIN number to each of Device A and Device B, in order to prevent active eaves dropping by checking whether both the numbers match, and concealed a link key by creating a link key from the PIN numbers input by the user, in order to prevent passive eavesdropping.
If the shape of Device A enables the device to display numbers and to input numbers and Yes/No while Device B cannot input numbers due to a reason for the device shape, the user can maintain the security level by describing the PIN number preliminarily in a manual, etc. of Device B and inputting the PIN number in Device A.
In these methods, however, there are problems on the usability and security. From the viewpoint of usability, there is a problem that if the user finds it troublesome to input the four-digit number to both the devices or uses the fixed PIN number, the user can hardly maintain the number. From the viewpoint of security, there is a problem that since there are at most 9,999 candidates for the link key, the link key may be identified by total check.
In SSP (Bluetooth core Specification version 2.1+EDR, Version 2.1 or later), the resistance to passive eavesdropping is improved and the security performance is enhanced by applying the public key encryption system to the link key creation to solve the above problem.